1. Field of the Invention
The present invention relates to a two-shaft gas turbine.
2. Description of the Related Art
As a background art in this technical field, there has been known a technique disclosed in JP-T-2007-505261 (patent literature 1). In this publication, there is the description “a power generation system is driven by a multi-shaft gas turbine engine including at least a first spool and a second spool. The first spool includes a turbine and a compressor which are mounted on the first shaft, and the second spool includes at least a turbine which is mounted on a second shaft which is not mechanically connected to the first shaft. A main generator is connected to one of the spools, and an auxiliary generator/motor is also connected to one spool. An operation of the engine is controlled using a speed control of the respective generators. The auxiliary generator/motor can be operated in a generation mode where power is extracted from the spool or in a motor mode where power is supplied to the spool” (see Abstract).